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I 10


many other mammals." In &7iidnat too, but not in Ornitho-
rhy fichus, the hemispheres are well convoluted, though the arrange-
ment of t'hese convolutions cannot be brought into line with what is
known concerning the convolutions upon the hemispheres of other
mammals. It had been stated that in. these animals, at least in
JSeJiidna, there were only two optic lobes, as in lower vertebrates,
instead of the mammalian four. The late Sir W. H. Flower set
this matter at rest,1 and showed that J&ch-idna was in this respect
typically mammalian. The absence of the corpus callos,um is

one of the principal features separ-
ating the Monotremes from other

The Monotremata are repre-
sented to-day by two types, Orn-itho-
rliyticfaiis and ItJeJiidnct,, which are
no doubt worthy of being placed in
separate families, Fossil remains
of the group (apart from the prob-
lematical Multituberculata) are only
known from Pleistocene times in
Australia, and consist of the bones
of a large species of jEcfoidna, and
some fragments of Ornithorhynchus,
indicating a smaller animal than

tho livinS riatypua

Fam. 1. Echidnidae. — This
family contains two genera, of which JEchidna is the older and
much the better known. The skin is abundantly covered with
spines, with which are mingled hairs. The snout is tapering,
the tail rudimentary, and the fingers and toes five in number.
The spur and gland upon the calcaneum are smaller than in
Ornithorhynchus. The claws are very strong, serving to tear
open the ants* nests, upon the inhabitants of which the Echidna
feeds, licking them, up with a long extensile tongue like that of
Myrmecophaga. In relation, to this habit the salivary glands are
enormously developed, arid indeed the animal lias been con-
founded with MyrmecopJiaga^ as the vernacular name " Australian
Anteater " exemplifies,

1 JProc. Zool. jSoc. 1864, p. 18.
a MyrmecQpJiaga, aculca+ta, waa the »amo given, bv Shaw.